The present invention concerns a friction vacuum pump having the characteristics of patent claim 1.
A friction vacuum pump of this kind is known from DE-A-31 24 205. As to the design of the opening of the intermediate inlet into the pumping chamber of the friction pump, it is stated that it is advantageous to provide an annular channel.
It is the task of the present invention to design the opening of the intermediate inlet into the pumping chamber of the friction vacuum pump in a preferred manner while at the same time taking two aspects into account. On the one hand the stator forming components in the area of the annular channel shall be designed in such a manner that they obstruct the gases entering into the pumping chamber as little as possible. On the other hand simple production of the components in the area of the annular channel shall be ensured.